A reamer is a drill bit that is normally drawn up through a predrilled hole by means of a rod extending in the hole. The reamer includes a carrier to whose upper side there is attached a drilling tool in the form of a number of so-called cutters. These cutters rotate against the rock surface, or stone surface, with which they are in abutment, as the reamer rotates in response to rotation of the rod. The cutters have a frusto-conical shape and are mounted with the largest diameter facing outwards, i.e. away from the rod disposed centrally in said carrier. The cutters are mounted on shafts accommodated in the attachments carried on the upper side of the carrier, with the axes of respective cutters extending mainly radially to the rod.
In turn, the cutters are provided with bearings by means of which the cutters are able to rotate about their respective axes. These bearings and also the seals between cutter and cutter shaft are kept lubricated with grease fed into the cutter interior. A shaft is usually filled with lubricating grease, by injecting the grease through a nipple at one end of the shaft and allowing the grease to flow out through a nipple hole on the other end of said shaft. This method functions very effectively provided that the cutter is not mounted within the reamer. However, when it becomes necessary to replenish or change the grease, which must done often when underground conditions are troublesome, it is difficult to reach the nipple seated at the narrower end of the cutter facing inwards towards the rod.